7odc

CRYSTAL STRUCTURE ORNITHINE DECARBOXYLASE FROM MOUSE, TRUNCATED 37 RESIDUES FROM THE C-TERMINUS, TO 1.6 ANGSTROM RESOLUTION


Although, 7odc is a 1 chain structure, the biological relevant molecule for 7odc can be assembled from the contents of the deposited coordinates by the application of crystallographic symmetry operations to give a dimer. It can be downloaded. A sequence alignment and structural comparison of mouse ornithine decarboxylase (mODC) to mouse Antizyme Inhibitor (AzI, 3btn) show high sequence identity (~50%) and structural similarity between mODC and AzI monomers (RMSD value is 1.6 Å). The structural comparison of mODC (red and lime ) to mouse AzI crystallographic dimer (mAzI, cyan and blueviolet ) is shown. Superposition of the interface of mAzI and mODC showing the inter-subunit variable loops (AzI residues 355–362 and 387–401). AzI loops are in black, and ODC loops are in yellow. The two AzI monomers (cyan, blueviolet ) have only 43 contacting residues (< 3.5 Å apart), while there are more contacts (83) between the two monomers of mODC (red , <font color='lime'>lime ). Moreover, the surface area buried by the two mODC monomers is significantly larger than the one buried by the AzI monomers. These features explain a very weak crystallographic AzI dimer. The zipper, formed by conserved hydrophobic residues in mODC, stabilizes its dimeric structure. These residues involve F397(B), Y323(B), Y331(A), Y331(B), Y323(A), and F397(A) (the names of the chains are in brackets). The residue Y331 in the <scene name='Antizyme_Inhibitor/Azi_odc1/3'>ODC zipper is substituted by S329 in AzI and interferes with the formation of a similar zipper in AzI. Hence, in <scene name='Antizyme_Inhibitor/Azi_odc1/4'>mAzI this hydrophobic zipper is absent. Many residues, participating in the ODC interdimer interface interactions, are conserved among the ODCs from variuos organisms, but in AzI these residues are not conserved. Furthermore, the AzI conserved residues do not participate in interdimer interactions. For example, mODC possesses <scene name='Antizyme_Inhibitor/Azi_odc1/5'>two salt bridges (K169–D364 and D134–K294) stabilizing the ODC homodimer. In AzI, these 4 corresponding residues (<scene name='Antizyme_Inhibitor/Azi_odc1/6'>K169-D362 and D134-K291, respectively) are also present, but are too far apart to form a salt bridge. The two AzI monomers are positioned farther apart, in comparison ot ODC monomers, preventing the formation of interdimer interactions.

About this Structure
7ODC is a 1 chain structure of sequence from Mus musculus. Full crystallographic information is available from OCA.